Critical Nitrogen Curve and Nitrogen Nutrition Index for Corn in Eastern Canada

• Published in: Agronomy journal 2008, Vol.100 (2), p.271-276
• Main Authors: Ziadi, N, Brassard, M, Belanger, G, Cambouris, A.N, Tremblay, N, Nolin, M.C, Claessens, A, Parent, L.E
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; corn; dry matter accumulation; Fundamental and applied biological sciences. Psychology; grain yield; model validation; Nitrogen; nitrogen nutrition index; nutrient availability; nutrient requirements; nutrient uptake; Nutrition assessment; plant growth; plant nutrition; soil fertility; Zea mays
• ISSN: 0002-1962; 1435-0645; 1435-0645
• DOI: 10.2134/agrojnl2007.0059

Plant-based diagnostic methods of N nutrition require the critical N concentration (Nc) to be defined, that is the minimum N concentration necessary to achieve maximum growth. A critical N curve (Nc = 34.0W-0.37 with W being shoot biomass in Mg DM ha-1), based on whole plant N concentration, was determined for corn (Zea mays L.) in France. Our objectives were to validate this critical N curve in eastern Canada and to assess its plausibility to estimate the level of N nutrition in corn. Shoot biomass and N concentration were determined weekly during the growing season at three sites for 2 yr (2004 and 2005); four to seven N treatments were used at each site. Data points were divided into two groups representing either nonlimiting or limiting N conditions according to significant differences in shoot biomass at each sampling date. All data points included in the limiting N group were under the critical N curve and most data points of the nonlimiting N group were on or above the critical N curve, hence confirming the validity of the critical N curve determined in France. The nitrogen nutrition index (NNI), calculated as the measured N concentration divided by the predicted Nc, ranged from 0.30 to 1.35. A significant relationship between relative grain yield (RY) and NNI (RY = -0.11 + 1.17 NNI if NNI < 0.93 and RY = 0.98 if NNI > 0.93; R2 = 0.89) was determined. The critical N curve from France is valid in eastern Canada and the NNI calculated from that curve is a reliable indicator of the level of N stress during the growing season of corn.